Judging Peripheral Change: Attentional and Stimulus-Driven Effects

1
Judging Peripheral Change Attentional and
Stimulus-Driven Effects
Poster 26.314 Abstract 413
Jenna Kelly Nestor Matthews
Department of Psychology, Denison University,
Granville OH 43023 USA
Discussion
Introduction
Method
Experiment 1 Temporal Asynchrony Alone
Experiment 2 Spatial vs. Temporal
Previous research has revealed performance
advantages for stimuli presented across
(bilateral) rather than within (unilateral) the
left and right hemifields on a variety of spatial
attention tasks, including alphanumeric symbol
identification (Awh Pashler, 2000), conjunction
and shape identification (Kraft et al., 2005),
multiple object tracking (Alvarez Cavanagh,
2005), Gabor detection and orientation
discrimination (Reardon et al., 2009), and visual
crowding (Chakravarthi Cavanagh, 2009). Here,
we probed for a similar advantage in a temporal
attention task. Whether temporal tasks should
exhibit the same bilateral advantage is
non-obvious because temporal and spatial
attention have different properties (Aghdaee
Cavanagh , 2007). Some of these hemifield
effects emerge only in the presence of
distracters. It may be important whether the
distracters add difficulty in a task-relevant
way task-irrelevant difficulty may not compete
for attentional resources enough to generate a
bilateral advantage. Evidence from Taya et al.
(2009) and Reardon et al. (2009) supports the
importance of task-relevance in driving the
observed hemifield effects. Here, we look
for hemifield effects in a temporal attention
task alone and in comparison to a spatial
attention task, with a particular interest in the
distinction between the properties of temporal
and spatial attention and the impact of
task-relevant difficulty.
When distracters were absent, proficiency
(d/RT) was significantly lower in the diagonal
condition than in either of the bilateral or
unilateral conditions, which were statistically
indistinguishable. This oblique effect was
eliminated in the presence of either distracter
type but maintained with the addition of the
concurrent spatial task. The lower proficiency in
the diagonal conditionin which targets were in
opposite hemifieldsprevents the attribution of
this effect to laterality. This pattern differs
from that observed in previous spatial attention
tasks, suggesting that the properties of spatial
and temporal attention may differ. We seem
to have found an oblique effect, like that of
Westheimer (2003), for a task in which
orientation is determined by the entire
configuration rather than by any of the
components, and we have extended this sort of
oblique effect to a timing comparison. It is
possible that the effect observed here is
actually one of distance while targets are the
same distance from fixation across laterality
conditions, the distance across which the
comparison is made is v(2) times longer on
diagonal trials than on bilateral or unilateral
trials. This deserves further consideration but
may be tentatively refuted by the results of
Kraft et al. (2005), which suggest that
target-target distance may affect performance
within but not between hemifields. Our apparent
oblique effect might also result from the
collinear relationship between the two targets
and fixation on diagonal trials, which is not
present on either bilateral or unilateral trials.
This cannot be refuted by our data but would
predict a counterintuitive effect of shifting the
fixation point to a location horizontally or
vertically intermediate to a pair of targets if
collinearity produces a performance deficit, then
pairs of targets closer to fixation will be
associated with lower performance than more
distant targets that are not collinear with
fixation. Such a finding would be surprising.
Regardless of the reason for the lower
performance on diagonal trials in this task, it
is important to note that the effect generalizes
across spatial and temporal attention tasks,
which suggests that the two types of attention
may share some properties. Even though the
distracters and multitasking each made the task
more difficult, the cardinal advantage was
eliminated only by distracters. Thus, it is not
task difficulty per se that drives the effect. It
may be that the distracters, but not the
concurrent spatial frequency judgment task,
provides task-relevant difficulty that generates
the observed oblique effect. The importance of
task-relevant difficulty has also been shown for
spatial attention-dependent tasks (e.g. Kraft et
al., 2005).
Experimental Details
Training Paradigm

• Discriminanda high (89.76 Michelson)
  contrast,14.55 deg diagonally from fixation,
  max/min luminances 108.00, 5.83 cd/m2
• Participants 23 Denison University
  undergraduates
• IVs 3 (Laterality) x 3 (Distracter)
• Laterality Bilateral , Unilateral, Diagonal
• Distracter Absent, Static, Dynamic

• Participants 19 Denison University
  undergraduates
• IVs 3 (Laterality) x 2 (Task) x 2 (Day)
• Task Spatial vs. Temporal
• Day2 (task blocked) vs. 3 (task unknown until
  prompt)

Results
References
Experiment 1 Temporal Asynchrony Alone
Experiment 2 Comparing Tasks and Days
Experiment 2 Day 3
Aghdaee, S. M., Cavanagh, P. (2007). Temporal
limits of long-range phase discrimination across
the visual field. Vision Research 47,
2156-2163. Alvarez, G. A., Cavanagh, P. (2005).
Independent resources for attentional tracking in
the left and right visual hemifields.
Psychological Science 16, 637-643. Awh, E.,
Pashler, H. (2000). Evidence for split
attentional foci. Journal of Experimental
Psychology Human Perception and Performance 26,
834-846. Chakravarthi, R., Cavanagh, P. (2009).
Bilateral field advantage in visual crowding.
Vision Research 49, 1638-1646. Kraft, A., et al.
(2005). Interactions between task difficulty and
hemispheric distribution of attended locations
implications for the splitting attention debate.
Cognitive Brain Research 24, 19-32. Reardon, K.
M., Kelly, J. G., Matthews, N. (2009).
Bilateral attentional advantage on elementary
visual tasks. Vision Research 49, 692-702. Taya,
S., Adams, W. J., Graf, E. W., Lavie, N.
(2009). The fate of task-irrelevant visual
motion Perceptual load versus feature-based
attention. Journal of Vision 9, 1-10. Westheimer,
G. (2003). Meridional anisotropy in visual
processing Implications for the neural site of
the oblique effect. Vision Research 43,
2281-2289.
Laterality x distracter interaction effect F (4,
88) 2.520, p 0.047, partial ?2
0.103 Laterality effect, distracters absent F
(2, 44) 3.457, p 0.040, partial ?2
0.136 Distracter main effect F (1.344, 29.566)
13.146, p lt 0.0005, partial ?2 0.374
Laterality main effect F (2, 36) 17.304, p lt
0.0005, partial ?2 0.490 Day main effect F
(1, 18) 38.032, p lt 0.0005, partial ?2
0.679 Laterality x Task x Day F (2, 36) 0.473,
p 0.627, partial ?2 0.026
F (2,36) 12.861, p lt 0.0005, partial ?2 0.417
http//denison.edu/matthewsn/spacetimeattentionvs
s2010.html